Airplane power dolley



Sept. 29, 1964 A. DUGGAR, JR

AIRPLANE POWERDOLLEY 2 Sheets-Sheet 1 Filed March 21, 1962 K 6 w w Kw Cm0 5E W LN 0 R 5 O P ET E 5T 0 n N N an O .4 Mg

P 1964 A. DUGGAR, JR 3,150,734

AIRPLANE POWER DOLLEY Filed March 21, 1962 2 Sheets-Sheet 2 v INVENTOR.I Amps/ saw Dues/113R BY United States Patent 3,150,734 AIRPLANE POWERDOLLEY Anderson Duggar, Jr., 935 S. Reading Road, Birmingham, Mich.Filed Mar. 21, 1962, Ser. No. 181,296 3 Claims. (Cl. 180-11) Thisinvention relates to tow sticks for moving airplanes on the ground. Itis intended to be easily attached to a ground wheel of the plane and tomove the plane by power derived from a source carried by the tow stick.Examples of tow sticks of the general character to which the inventionrelates are shown in the patents to Palmiter, 2,920,845, and Wirkkala,2,949,972.

In the devices of this character which have come to my attention, thetow sticks have been diflicult to transport to and from the plane, orhave been difiicult to attach to the plane in operating relation, orboth. The invention seeks to overcome these and other disadvantages ofknown tow sticks and has among its objects the provision of an improvedand convenient tow stick which:

(1) Can be easily transported to and from a plane;

(2) Can be easily and eifectively attached to the plane;

(3) Can be raised easily into working position by power devices carriedby the tow stick;

(4) Is supported out of contact with the ground when towing the plane;

(5) The weight of the tow stick and its power devices is used to urgepower driving means into effective contact with the wheel of the plane,and especially one in which the distribution of the weight of the powerdevices on the tow stick with respect to the point of attachment of thestick to the plane automatically urges the power driving device intoeffective friction contact with the wheel of the plane, and so providesenough friction effectively to move the plane; and

(6) Having a battery-driven electric motor with an arrangement forkeeping the batteries substantially level during all movement andoperation of the tow stick.

a generally U-shaped frame 10, the arms of which are bent to formportions 11 and 12 and having a bight 13 forming a handle. At the tipsof the U are fasteners for securing the tow stick to the plane. Thefasteners may conveniently include an arm 14 welded to each arm of theframe and projecting inwardly and carrying a pin 16 which is to beattached to the plane in any suitable manner, for example by beinginserted upwardly into an eye 18 (FIGURE 1) welded to, or formed in, thefork or other support 20 which carries the steerable nose wheel 22 ofthe plane 24. The pins and eyes form fastening means securing the stickto the plane along a horizontal pivot line above the wheel and adjacentthe tread of its tire, to permit vertical movement of the handle 13. Theframe portion 12 is intended to be substantially horizontal when the towstick is in position to move a plane and the angle between the portions11 and 12 is such that the handle is then disposed at a convenientheight for an operator.

As shown in FIGURE 2, a driving drum 26 is journalled on the frame 10.Its axis of rotation is in front of the vertical plane of the eyes 18when the tow stick is in Other objects of this invention will appear inthe following description and appended claims, reference being had tothe accompanying drawings forming a part of this specification whereinthe same reference character always designates the same part throughoutthe various views.

In the drawings:

FIGURE 1 includes a schematic side elevation of a tow stick embodyingone form of the invention, shown in inoperative position;

FIGURE 2 shows the tow stick in the position in which it starts to belifted by power to operative position;

FIGURE 3 shows the tow stick attached to the plane inoperative positionfor towing;

FIGURE 4 is an enlarged detail in perspective, partly broken away,showing one form of fastener for securing the tow stick to the plane;

FIGURE 5 is a perspective view of the tow stick; and

FIGURE 6 is a schematic perspective, partly broken away, of one form ofdriving drum in contact with a ground wheel of the plane.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in construction norapplication to the details nor arrangement of parts shown and describedherein for illustration, since the invention is capable of otherembodiments and of being practiced or carried out in various ways. Also,it is to be understood that the terminology employed herein is for thepurpose of description only and does not limit the invention.

Referring to FIGURE 5, the tow stick may include operating position andthe surface of the drum is in contact with the surface or tread of thenose wheel at a point substantially removed circumferentially from theeyes 18 and substantially below the horizontal plane of the eyes. Bycircumferentially removed I mean that there is a distance from the pointof contact of the driving drum with the nose wheel, along the tread orcircumference of the nose wheel, to that point on the tread of the nosewheel which is nearest to the eyes 18. This spacing or distance enablesthe entire stick to pivot about the eyes 18 to bring the drum into firmand yielding contact with the wheel. It also enables the entire stick topivot about the point of contact with the wheel to insert the pins 16into the eyes 18 when attaching the tow stick to the plane, as will beexplained. An electric motor 28 is attached to the frame forward of thedriving drum and is connected to rotate the driving drum in eitherdirection through a reduction gear which will be described.

A battery support 30 hangs from a pivot bar 32 which is located betweenthe handle of the tow stick and the motor. This maintains upright,regardless of the position of the tow stick, any suitable electricstorage battery 34 placed in this support. The battery is connected tothe motor by any suitable leads 36 in circuit with a forward and reverseswitch 38 placed on the handle. A control box 40, attached to the framein any suitable way, may contain a two-speed switch 42 for selecting thespeed at which the forward and reverse switch rotates the drum. Thecontrol box may also include a lock switch 44 which may also control alight 46. Any suitable battery charger may be carried in the control boxfor connection with a power line to charge the battery.

The entire assembly or tow stick is supported by a pair of ground wheels48 journalled on an axle 50, supported in a pair of U-shaped bracketsdepending from the frame. Preferably the axle 50 is disposed so thatwhen the portion 12 of the frame is substantially horizontal the axle isin a vertical plane which includes the center of gravity of theassembly, or is close to it.

Preferably the motor and driving drum are mounted as a unit on asub-frame which is attached to the frame 10 and can easily be removed.As shown in FIGURE 5. the sub-frame includes plate 60 attached to oneend bell of the motor and in turn attached to a U-shaped bracket, theends of which terminate in side arms 64, each of which carries a bearing66 which supports the shaft 68 on which the drum 26 rotates. The sidearms 64 may be bolted to the arms of the frame 10. The drum may consistof two frusto-conical friction elements 70 disposed on either side of aworm housing 72 secured to the plate 60 and containing a reversible wormwheel 74 keyed to the drum and meshing with a reversible worm '76forming part of the shaft. of the motor, or secured to it. Thisarrangement provides a driving torque at the longitudinal center of thedrum and simplifies the construction and arrangement of the necessarydrum bearings and connection of the drum to the. motor through aspeedreducing gear.

In operation, the tow stick is wheeled to the plane and the drum isplaced against the nose wheel as shown in FIGURE 2. The drum is thenrotated slowly forward, or counter-clockwise as FIGURE 2 is seen, whilethe handle end of the frame is supported by the operator. This causesthe drum to roll up the periphery of the nose wheel and both raises theground wheels 48 off the ground and places the pins 16 just below theeyes 13. The frusto conical driving elements engage the nose wheel atspaced points on opposite sides of the center of the tread. Thisprovides a stable contact between wheel and drum which enables the drumto roll up the tread of the wheel securely and without falling off. Thehandle is then lowered slightly to project the pins into the eyes frombelow. The tow stick is now supported entirely by the plane. The arms14, together with the drum resting on the nose wheel, support the entireweight of the tow stick. The pins and the eyes can transmit thrusteither forward or backward to the fork 20 when the driving drum isrotated.

Because the driving drum is located between the pins 16 and the motorand battery, the weight of the battery and motor urges the drum forciblyagainst the nose wheel to provide sufficient friction to drive the nosewheel from the drum and so move the plane. Because the wheels are 01fthe ground the plane may be steered by simple movement of the handle tothe right or left as the plane is being towed.

To remove the tow stick from the plane, the handle is raised slightly tolower the pins out of the eyes, and then the drum is driven backward tolower the wheels to the ground.

I claim:

1. In a power tow stick for moving over the ground an airplane having asteering wheel mounted on a rotatable support, the combination of aframe, attaching means on the frame for fastening the frame to thesupport at a horizontal pivot line above the wheel, a driving drumjournaled on the frame and horizontally spaced from the support, arolling ground support for moving the frame to place the drum infriction contact with the wheel at a point circumferentially spaced fromthe support, and means for lifting the tow stick to place the attachingmeans at said pivot line, said last-mentioned means including a motorfor rotating the driving drum in contact with the wheel.

2. In a power tow stick for moving over the ground an airplane having asteering wheel mounted on a rotatable support, the combination of aframe, attaching means on the frame for fastening the frame to thesupport at a horizontal pivot line above the wheel, a driving drumjournaled on the frame and horizontally spaced from the support, arolling ground support for moving the frame to place the drum infriction contact with the wheel at a point circumferentially removedfrom the attaching means, and means for. raising the ground support fromthe ground, said last-mentioned means including a motor for rotating thedriving drum in contact with the wheel.

3. In a power tow stick for moving over the ground an airplane having asteering wheel mounted on a rotatable support, the combination of aframe including a handle, attaching means on the frame for fastening theframe to the support at a horizontal pivot line above the wheel, adriving drum journaled on the frame and located between the handle andthe attaching means, a rolling ground support for moving the frame toplace the drum in friction contact with the wheel at a pointcircumferentially spaced from the support, and means for raising theground support from the ground including means for rotating the drum incontact with the wheel, said driving drum being placed between theraising means and the attaching means so that the weight of the raisingmeans urges the drum into frictional engagement with the wheel both whenthe tow stick is supported by the ground support and the drum on thewheel, and when the tow stick is supported by the attaching means andthe drum on the wheel.

References Cited in the file of this patent UNITED STATES PATENTS2,712,357 Fulton July 5, 1955 2,920,845 Palmiter Jan. 12, 1960 2,949,972Wirkkala Aug. 23, 1960 3,025,922 Savidge Mar. 20, 1962

1. IN A POWER TOW STICK FOR MOVING OVER THE GROUND AN AIRPLANE HAVING ASTEERING WHEEL MOUNTED ON A ROTATABLE SUPPORT, THE COMBINATION OF AFRAME, ATTACHING MEANS ON THE FRAME FOR FASTENING THE FRAME TO THESUPPORT AT A HORIZONTAL PIVOT LINE ABOVE THE WHEEL, A DRIVING DRUMJOURNALED ON THE FRAME AND HORIZONTALLY SPACED FROM THE SUPPORT, AROLLING GROUND SUPPORT FOR MOVING THE FRAME TO PLACE THE DRUM INFRICTION CONTACT WITH THE WHEEL AT A POINT CIRCUMFERENTIALLY SPACED FROMTHE SUPPORT, AND MEANS FOR LIFTING THE TOW STICK TO PLACE THE ATTACHINGMEANS AT SAID PIVOT LINE, SAID LAST-MENTIONED MEANS INCLUDING A MOTORFOR ROTATING THE DRIVING DRUM IN CONTACT WITH THE WHEEL.